The present invention is generally directed to track-type machines. More particularly, the present invention is directed to a drive assembly for a track-type machine.
Traditionally, track-type machines have been driven by a power source contained within the body of the track-type machine, as seen, for example, in U.S. Pat. No. 3,828,873. Usually, these power sources have been mechanically coupled to input shafts that extend through the machine frame and engage a pair of sprockets. These sprockets generally are supported on opposite sides of the machine frame and are rotatably mounted to the machine frame. The sprockets may directly or indirectly drive an endless track about a roller frame to provide movement of the machine. Each roller frame is generally supported behind its midpoint by a pivot shaft, which extends from the machine frame. Each roller frame is also generally supported in front of its midpoint by an equalizer bar attaching both roller frames together. The midpoint of the equalizer bar is attached at the lateral midpoint of the machine frame. The equalizer bar controls the rotation of each roller frame about its pivot shaft. As the front of one roller frame is forced to rise by externally applied forces or uneven ground, the opposite roller frame is forced to fall by the equalizer bar. Each roller frame has idler wheels affixed to each end to support the endless track as it rotates.
One limitation of having a sprocket that is mounted to the machine frame of the track-type machine is that the roller frame is constrained in its movement. For example, when the track type machine encounters an obstacle, on one side, the front of that side roller frame is urged upward and the front of the opposite side roller frame is urged downward by the equalizer bar. This motion is restricted by the proximity of the rising rear idler to the fixed position sprocket. This restriction limits the height of obstacles the machine can negotiate. This limitation also increases the harshness of the ride the machine operator feels as obstacles are encountered.
One alternative approach for providing power to drive a track-type machine is to have a motor cantilevered from the roller frame, as seen in U.S. Pat. No. 4,739,852. In this arrangement, the motor is arranged such that the axis of rotation of the power source is parallel to the axis of rotation of a drive system. However, one disadvantage of this arrangement is that the size of the power source is constrained. In addition, this type of machine does not have a roller frame that can pivot when it encounters an obstacle in the working environment.
The present invention solves one or more of the problems associated with existing track-type machine designs.
One aspect of the present invention is directed to a drive assembly including a roller frame, a motor located on the roller frame, and a drive system located on the roller frame. The drive system may be driveably engaged with the motor. The motor may have a longitudinal axis substantially aligned with a longitudinal axis of the roller frame.
Another aspect of the present invention is directed to a track-type machine including a machine frame and a roller frame supported on the machine frame in a manner to provide for pivotal movement of the roller frame relative to the machine frame. A motor may be located on the roller frame and may be driveably engaged with a drive system located on the roller frame. An endless track may be driven by the drive system to provide locomotion for the track-type machine.
In yet another aspect, the invention is directed to a track-type machine including a machine frame and a roller frame supported on the machine frame. The roller frame may include a housing. A motor may be located on the roller frame and may be driveably engaged with a drive system, which may be supported within the housing of the roller frame. An endless track may be driven by the drive system to provide locomotion for the track-type machine.
The present invention is also directed to a method of driving a track-type machine having a machine frame. The method includes providing at least one drive assembly including a roller frame supported on the machine frame in a manner to provide for pivotal movement relative to the machine frame, a motor located on the roller frame, a drive system located on the roller frame and driveably engaged with the motor, and an endless track driven by the drive system to provide locomotion for the machine. The method also includes providing power from the motor on the roller frame to the drive system. The drive system drives the endless track.